In the packaging of pharmaceutical products, such as tablets, capsules, dragees or the like, so-called press-to-eject packages are preferably used. These packages are fabricated, filled and sealed on one and the same machine in such a manner that a thermoplastically deformable foil strip, after being heated, is provided at a forming station with deep-drawn depressions, which are then filled with tablets or the like and then sealed by pressing a foil cover strip, preferably of aluminum, over them. Finally, the desired package sizes are stamped out from the strips and then generally delivered to a cartoning machine and packed, either individually or in groups, in folding boxes. In order to identify the contents, the foil cover strip is provided with an appropriate printed legend. It is of utmost importance that the foil cover strip be guided together with the lower foil strip--that is, the one having the container-like recesses filled with tablets or the like--in such a way that each of the package units so formed contains a complete legend. In order to provide continuous monitoring of the preferably continuous advancement of the foil cover strip, markings which can be scanned by photoelectric devices are incorporated in the legend. Means are further provided which exert influence on either the foil cover strip or the lower foil strip having the container-like recesses, depending on the outcome of the scanning of the markings on the foil cover strip. This influence may be exerted such that one of the two continuously advanced foil strips is briefly either accelerated or slowed down. It has also already been proposed that the foil cover strip be shortened in length by forming a loop (German Pat. No. 14 61 923). In that case, the loops are each placed between two package units, so that when the package units are stamped out later from the larger strip, the loops are cut away and discarded. This manner of operation, however, causes a relatively great waste of foil, which makes for uneconomical production of the tablet strip packages; this is particularly true when aluminum is used, as is the case at present.
Another known apparatus (German Auslegeschrift No. 26 53 196) makes use of the fact that the aluminum foil cover strip is stretchable within certain limits. The distance between sequential printed legends on this foil cover strip is shorter than the length of the packages to be closed, so that the deviation in spacing of the legends can be corrected by stretching the foil cover strip. When a cover strip of metal foil is used (foil cover strip) in the known apparatus, this stretching is accomplished by disposing a multiplicity of stationary parallel rods in the stretching zone; these rods have transversely disposed edges engaging opposite sides of the metal strip such that the metal strip is deflected in a zigzag pattern. These rods thereby accomplish a stretching of the foil cover strip, and this stretching effect may be increased or decreased, depending on what is required, by varying the tension of the foil cover strip. The regulation of the tension and thus of the extent to which the foil cover strip is stretched is accomplished by braking a roller; the braking times are controlled in accordance with a photo cell which scans the markings on the foil cover strip.
A great disadvantage of this known apparatus is that as a result of the increase in tension--since stretching can be attained only in this way--scratch and abrasion marks are made on the foil cover strip. Furthermore, the danger that the foil cover strip will tear in the course of such an operation cannot be ruled out entirely. There is also an uncertainty factor relating to stretching the foil cover strip by varying the strip tension in accordance with the braking of the roller. Unequivocally replicable values can be attained only with difficulty in such an apparatus.
It would be desirable at this time to have a method, and a corresponding apparatus for performing the method, in which the stretchability of the aluminum foil cover strip is provided, while the two continuously advanced foil strips are guided in combination, incorporating a register, without damaging the foil cover strip in so doing.